.box1 {
    width: 100px;
    height: 100px;
    background: url('../images/vue.jpg') no-repeat ;
    background-size:100%
}

.box2 {
    width: 200px;
    height: 200px;
    background: url('../images/react.png') no-repeat;
    background-size: 100%
}

.box3 {
    width: 300px;
    height: 300px;
    background: url('../images/angular.jpg') no-repeat;
    background-size:  100%
}
